Nobody has proven anything- people have simply stated that they believe the opposite or have had experiences that suggest the opposite.
No, you said "obviously racism is more prevalent in the South", which is untrue. I grew up in Mississippi, and have been living in Augusta, Ga., on the SC line, for the past 16 years. I stayed after I ETS'd from the US Army. I've also traveled to MANY states as a defense contractor, a lot of those up north. Taunton, Massachusetts, Tinton Falls/Eaton, New Jersey, Pennsylvania from Harrisburg to Philly, and many, many other areas. Who do you think would be more of an authority on the subject? You, who spent one year here but has relatives here? Or people that actually live in the South? There's a reason black people are moving back down south. There's a reason Herman Cain is VERY liked as a presidential candidate down south. There's a reason our suburbs aren't lily-white like many I saw up north. My suburb of 500K+ homes is about 1/4 black. Could be many reasons, could be that many towns in the South have military installations around them. Could be that many southern people serve in the military, an entity that instills a "we're all equally worthless as f**k" mentality, could be that it's staunchly Republican in the South. Then again, some of the places that do have race issues, from "my" experience, are the ones that are under Democratic control.
We can all make assumptions, but to say a definitive statement such as racism is more prevalent in the south, with nothing to go on other than your one little year in Atlanta and having relatives, is nothing but baseless conjecture on your part and should be perceived as such.